Field of Invention
Various embodiments of the present invention generally relate to an electronic device, and more particularly, to a semiconductor memory device.
Description of Related Art
Semiconductor memory devices are classified into volatile memory devices and nonvolatile memory devices.
Volatile memory devices operate at high write and read speeds, but they lose stored data when the power is off. Thus, nonvolatile memory devices are used to retain data regardless of power on/off conditions. Examples of the non-volatile memory include a read only memory (ROM), a mask ROM (MROM), a programmable ROM (PROM), an erasable programmable ROM (EPROM an electrically erasable and programmable ROM (EEPROM) a flash memory, a phase-change random access memory (PRAM), a magnetic RAM (MRAM), a resistive RAM (RRAM) and a ferroelectric RAM (FRAM). Flash memories are categorized into NOR or NAND type.
Flash memories have the advantages of both a RAM and a ROM. For example, flash memories may be freely programmed and erased similar to a RAM, and similar to a ROM, flash memories may retain the stored data even when they are not powered. Hash memories have been widely used as the storage media for portable electronic devices, such as, digital cameras, personal digital assistants (PDAs) and MP3 players.